Tuesday, November 13, 2007

diary of a man whose passions pull him in many directions

First I had to over come this:Thanks D.

Now this:

I had been putting off working on the diamondiod parts because the performance wall on my system is just a little too high for it to be enjoyable. However I may be able to score some time on a really tricked out system, so I'll give it another shot.

2 comments:

That's what we do. So, was the problem density/van der Waals overlap or an odd minimization?

Three ideas to proof-more-principle.

1. The obvious one, get rid of some gas (I assume this is running already)!

2. Try a system of mixed Noble gases, which will reduce the degrees of freedom in the system and provide very simple mass/volume differences. Noble gases encapsulated in C60 would be another idea, but I suspect the mass differences would be so small that you'd run out of significant digits in the/any MD code.

3. Try slowing down the rotation. If the electrostatics are working right, then another sorting mechanism will involve the stickiness of certain molecules to maxima in the electron density of the nanotube (the pi-systems over each six-member ring). At sufficiently slow rotations, a molecule will settle into a surface minimum and then stay there as the binding force to the wall is stronger than the force "down" to the nanotube cap. Assuming that the binding strength is significant, the molecule won't crawl out of its potential well at slow speeds and will migrate slowly along a shortest-path distance to the bottom as the downward force just enables the inching of the molecule between neighboring six-member rings (think The Price Is Right's Plinko Board, quite possibly the most profound example of quantum phenomena on daytime TV). You might be able to bet-hedge by throwing hydrogen fluoride (HF) into the system (the fluorine pulls most of the charge from the H, the H becomes very positive, the H sticks to anything significantly negative, i.e. the pi-system. That’s also the origin of the herringbone geometry in benzene crystals).

It was a problem with an overlap. This sim was with noble gases, He and Ar. Not all of them flew out and there was a distinct stratification on the hand full that stayed in on the last frame of the sim.